Carburetor



April 16, 1945 E. A. SWITZE R CARBURETOR Filed Jan. 23, 1951 Patented Jan. 23, 1951 CARBURETOR Elch-ed A. Switzer, Vancouver, British Columbia, Canada Application April 16, 1945, Serial No. 588,429

6 Claims.

This invention relates to an improved carburetor for internal combustion engines.

It is an object of the present invention to provide a carburetor comprising adjustable automatic means. operated by the degree of suction in the mixing chamber, for controlling the ratio of fuel to air in the mixture.

It is also an object of the present invention to provide an improved carburetor in which means are provided for vaporizing the fuel before admission to the mixing chamber, thus eliminating need for a float chamber, and improving the thermo-dynamic qualities of the resulting mixture to provide more efficient combustion.

It is a further object of the invention to provide adjustable automatic means for maintaining substantially constant the temperature of the vaporized fuel supplied to the mixing chamber.

Other features and objects of the invention will appear from the following description with reference to the accompanying drawings, in which:

Fig. 1 is a cross sectional view of a carburetor according to the invention taken on the line i-i in Fig. 2, and

Fig. 2 is a sectional plan view taken on the line 2-2 in Fig. 1.

The carburetor unit shown in the drawings consists basically of a mixing chamber il] and a vaporizing unit ll. 'vaporized fuel is fed from the latter to the mixing chamber by means of fuel supply line I2 and fuel inlet tube i3 suitably mounted in the walls of the mixing chamber and extending centrally across it (see Fig. 2). The 'escape of vaporized fuel from tube i3 is effected vthrough a suitable orifice and is controlled by a metering pin l5 carried by a stem i3 the lower end of which extends through a suitable hole in a guide bar Il mounted in the walls of the mixing chamber below the usual Venturi throat I8. A spring i9 urges the metering pin y upwardly to close the crioe i@ at its upper or reduced end. Pin l5 is provided with extension 29 guided in a bore 2i formed in a, guide j through the perforated cap is a valve stem 2l on which is mounted an air inlet valve 2t adapted to be moved downwardly against spring 23 to admit air to the mixing chamber when suction is created therein. The lower end of the valve stem 27 is supported by a tubular guide sleeve 3B fitted over the guide member 22, and, like it, suitably mounted on the tube I3. At its lower end the guide sleeve 32 is provided with a flange 3l retaining spring 29 the other end of which bears against the lower face of the air inlet Valve 28 urging it to the seated position shown in Fig. 1.

The air inlet valve 23 is disc-shaped, and has extending through it a plurality of holes 32 which are covered by an auxiliary disc 33 normally held in contact with the top surface of the valve member 28 to close the holes 32, by a relatively weak spring 3l?. The disc 33 which is mounted to slide on the stem 21 normally rides up and down with the valve 28 and stem 2l, but on occurrence of a sudden increase in `pressure in the mixing chamber, such as might be caused by a backfire, the disc 33 is forced upwardly away from valve 28, thereby clearing the holes 32 and allowing the gases to escape harmlessly therethrough. u

The air inlet valve 28 is connected to the metering pin l5 so that the latter is operated to admit vaporized fuel to the mixing chamber through orice lil in a proportion dependent on the volume of air admitted by the valve 28, theY connection being as follows: An arm 35 having arcuate top and bottom surface is pivoted at 35 at one side of the mixing chamber, and extends across the chamber as appears from Fig. 2. Near to the end which is opposite to the pivot 33 the top surface of the arm 35 is engaged by a follower member 3'5" connected to valve member 23 to move up and down with it and to pivot the arm 33 downward accordingly. The lower arcuate face of the arm 35 is engaged by a second follower 38 which is slidable from end to end of the lower arcuate surface and is connected to shoulder 39 of metering pin l5 by means of link it pivotally connected to such shoulder at 4I. The follower 33 is adjusted along the length of the lower arcuate surface of the arm 35 by means of a manual control cable 32 which projects through a packing gland 43 shown in dotted lines in Figure 2.

It will be observed that as pressure is reduced in the mixing chamber, and thus the air inlet -valve 28 is moved downwardly, the metering pi'n i5 is moved away from its seating in the orifice i4 in order to admit vaporized fuel to the mixing chamber in proportion to air admitted by opening of the valve 28. It will be further observed that the relationship between the opening of the orifice I 4 and the opening of the air valve 28, and thus the fuel air ratio, may be varied by adjusting the position of the follower 38 along the lower` arcuate surface of the arm 35. Thus if the follower 38 be positioned at the extreme left end of arm 35, that is, at the opposite end of the position shown in'Figure 1, downward niovement of air inlet valve 28 causes relatively little movement of the metering pin I and thus relatively little opening of the orifice I4. In Fig. 1 the follower 38 is shown in a position which would cause maximum movement of the metering pin I5 for a given movement of the air inlet Vvalve 28, this resulting in a maximum obtainable fuel air ratio in the combustion mixture.

The vaporizing unit II consists of a double helical coil 44 made of fuel line tubing and connected in the fuel line ,supplied by the conventional fuel pump (not shown). The outer helical coil is connected to the supply line from the fuel -,pump at 45 and is connected in the line I2 leading to the tube I3 at 4'6.

The vaporizing unit II is provided with a base 41 rigidly connected to the mixing chamber I by screws 48. The base 41 is provided with an inlet port 49 suitably connected to be `supplied with exhaust gases from the exhaust manifold of the internal combustion engine, and an exhaust port 50. The outer wall of the vaporizing unit is formed by a tubular cover member 5I supported on the base 41 and closed at the top by a cap-52. Also mounted on .the base il is an inner tube 53 which lits within the outer helix of coil 44 and .around the inner helix. This inner tube 53 has a perforated cap 54, and both of the tubes 5I and 53 are held in Aposition on the base 4l by means of their respective caps 52 and 54. The inner cap 54 is engaged by flange 55 of rod 56 screwed into base 41 at 5l, and the outer cap 52 is held in position by screw 58 screwed into 'the end of rod 56. It will be seen'that the members 5I and 53 with their caps 52 and 54 can be readily removed for inspection and cleaning purposes.

The exhaust ,gases on entering port 49 follow a course indicated by the arrows A and B up around the inner helix of tube 44 within the member 53, through the perforations in the cap 54, `downwardly as indicated by the arrows B in 'the space between the members 5i and 53 and thus around the'outer helix of the coil '44. Vand out the exhaust port 59. It will be observed that this arrangement provides that the hottest (that is the freshest) exhaust gases rst .come in contact with that part of the helical coil M which Acontains fuel about to be delivered to the inlet tube I 3 in the mixing chamber. It follows that fuel entering the vaporizing units from the fuel pump comes in contact with hotter gases as it progresses, and therefore ris .heated gradually and rapidly. In this manner it is insured that maximum effectiveness is obtained from the exhaust gases.

Mounted on the outside cf the cover member 5E is a thermostat 59 which is connected to a buttery valve (not shown) which regulates the supply .of exhaustgases to `port .4.9. This thermostat is adjustable and can be adjusted to keep the vaporized fuel supplied to the mixing chamber IIIv at a constant optimum temperature. The importance of this thermostatie `control is realized when itis `.considered :that since `the fuel in the :fuel inlet tube I3 is in a vaporized condition, acycording to .the .laws .of :gases .any .change in its;

temperature will cause a change in its pressure. This causes variations in the amount (by weight) of the fuel supplied to the mixing chamber I0 upon a given movement of the metering pin I5 and the air inlet valve 28 (the greater the fuel pressure, the greater being the amount of vaporized fuel admitted to the mixing chamber). This in turn causes a variation in the mixture and a corresponding loss in thermodynamic efficiency in the combustion. The provision of the termostatic control eliminates the possibility of such .variations of mixture by keeping the temperature, and therefore the amount of the vaporized fuel supplied substantially constant for any given .degree of suction in the mixing chamber.

What I claim is:

1. A carburetor for internal combustion engines comprising a mixing chamber, an air inlet valve for said chamber adapted to be opened in response to reductions .in pressure within said chamber, spring means urging said valve into the closed position, means supplying vapor-ized fuel to said mixing chamber, metering means controlling admission of said vaporized fuel, and adjustable means connecting said air inlet valve to said metering means to operate the latter according to opening of said air inlet valve to admit vaporized fuel to said mixing chamber in proportion to the admission of air thereto, said adjustable means connecting said air inlet valve and metering means comprising an arcuate member pivoted at one end at one side of said mixing chamber and engaged adjacent the other end by means in connection with said air inlet valve adapted to move said arcuate member towards said metering means onopening of said air valve, a follower member movable from one end to the other of said arcuate member and movable towards said metering means by said arcuate member, means for adjusting the position of said follower along the length of said arcuate member' and means connecting said follower to said metering means, said metering means being actuated on opening of said air inlet valve to a degree detei-mined by the adjustment of said follower member along the length of said arcuate member.

2. A carburetor for internal combustion engines comprising a mixing chamber, an air inlet valve for said chamber adapted to be opened in response to reductions in pressure within said chamber, spring means urging said valve into the closed position, means supplying vaporized fuel to said mixing chamber, metering means controlling admission of said vaporized fuel, and adjustable means connecting said air inlet valve to said metering means to operate the latter according to opening of said air inlet valve to admit vaporized fuel to said mixing chamber in proportion to the admission of air thereto, said means for supplying vaporized fuel to said mixing chamber comprising a housing, a fuel supply line, a double helical coil in said housing con--l nected in said fuel line, and means supplying heat to said double helical coil, and said adjustable means connecting said air inlet valve and metering means comprising an arcuate member pivoted at one end at one side of said mixing chamber and engaged adiacent the other end by means in connection with said air inlet valve adapted to move said arcuate member towards said metering means on opening of said air valve,

,a follower member movable from one end to the other `of said arcuate member and movable towards said metering means by said arcuate member, means .for adjusting the position of said follower along the length of said arcuate member and means connecting said follower to said metering means, said metering means being actuated on opening of said arr inlet Valve to a degree determined by the adjustment of said follower member' along the length of said arcuate member.

3. A carburetor for internal combustion engines comprising a mixing chamber, an air inlet valve for said chamber adapted to be opened in response to reductions in pressure within said chamber, spring means urging said valve into the closed position, means supplying Vaporized fuel to said mixing chamber, metering means controlling admission of said vaporized fuel, and adjustable means connecting said air inlet valve to said metering means to operate the latter according to opening of said air inlet valve to admit vaporized fuel to said mixing chamber in proportion to the admission of air thereto, said means for supplying vaporized fuel to Said mixing chamber comprising a housing, a fuel supply line, a double helical coil in said housing connected in said fuel line, and means for supplying hot gases to said housing and circulating the same therethrough around said double helical coils, and said adjustable means connecting said air inlet valve and metering means comprising an arcuate member pivoted at one end at one side of said mixing chamber and engaged adjacent the other end by means in connection with said air inlet valve adapted to move said arcuate member towards said metering means on opening of said air valve, a follower member movable from one end to the other of said arcuate member and movable towards said metering means by said arcuate member, means for adjusting the position oi said follower along the length of said arcuate member, and means connecting said follower to said metering means, said metering means being actuated on opening of said air inlet valve to a degree determined by the adjustment of said follower member along the length of arcuate member.

4. A carburetor for internal combustion engines comprising a mixing chamber, an air inlet valve for said chamber adapted to be opened in response to reductions in pressure within said chamber, spring means urging said valve into the closed position, means supplying vaporized fuel to said mixing chamber, metering means controlling admission of said vaporized fuel, and adjustable means connecting said air inlet valve to said metering means to operate the latter according to opening of said air inlet Valve to admit vaporized fuel to said mixing chamber in proportion to the admission of air thereto, said means for supplying vaporized fuel to said mixing chamber comprising a housing, a fuel supply line, a double helical coil in said housing connected said fuel line, means for supplying heat to said double helical coil, and a thermostatic control device adapted to maintain the vaporized fuel supplied to said mixing charnber at a substantially constant temperature.

5. A carburetor for internal combustion engines comprising a mixing chamber, an air inlet valve for said chamber adapted to be opened in response to reductions in pressure within said chamber, spring means urging said valve into the closed position, means supplying vaporzed fuel to said mixing chamber, metering means controlling admission of said vaporized fuel, and adjustable means connecting said air inlet valve to said metering means to operate the latter according to opening of said air inlet Valve to admit vaporized fuel to said mixing chamber in proportion to the admission of air thereto, said means for supplying vaporized fuel to said mixing chamber comprising a housing, a fuel supply line, a double helical coil in said housing connected in said fuel line, means for supplying heat to said double helical coil, and a thermostatic control device adapted to maintain the vaporized fuel supplied to said mixing chamber at a substantially constant temperature, and said adjustable means connecting said air inlet valve and metering means comprising an arcuate member pivoted at one end at one side of said mixing chamber and engaged adjacent the other end by means connection with said air inlet valve adapted to move said arcuate member towards said metering means on opening of said air valve, a follower member movable from one end to the other of said arcuate member and movable towards said metering means by said arcuate member, means for adjusting the position of said follower along the length of said arcuate member, and means connecting said follower to said metering means, said metering means being actuated on opening of said air inlet valve to a degree determined by the adjustment of said follower member along the length of said arcuate member.

6. A carburetor for internal combustion engines comprising a mixing chamber, an air inlet valve for said chamber adapted to be opened in response to reductions in pressure within said chamber, spring means urging said valve into the closed position, said valve having at least one hole extending therethrough, an auxiliary valve disc on the outer surface of the inlet Valve normally covering the hole therein, spring means normally holding the valves together, said auxiliary Valve disc being adapted to uncover the hole on sudden increase of pressure in the chamber, means supplying Vaporized fuel to the mixing chamber, metering means controlling admission of the vaporized fuel, and adjustable means connecting said air inlet Valve to said metering means to operate the latter according to opening of said air inlet valve to admit vaporized fuel to said mixing chamber in proportion to the admission of air thereto.

ELDRED A. SWITZER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,803,240 Fenzel Apr. 28, 1931 1,874,238 Callahan Aug. 30, 1932 1,933,992 Mendez Nov, 7, 1933 2,000,901 Jones May 14, 1935 2,077,493 Rossi Apr. 20, 1937 2,085,243 Welke June 29, 1937 2,106,903 Tonkin Feb. 1, 1938 2,128,519 Adams Aug. 30, 1938 2,258,003 Dickson Oct. 7, 1941 2,311,315 Smith Feb. 16, 1943 2,341,177 Cope Feb. 8, 1944 FOREIGN PATENTS Number Country Date 378,766 Italy Feb. 23, 1940 

